1. Field of the Invention
This invention relates to an image formation apparatus having an image bearing member and process means acting on the image bearing member.
2. Description of the Prior Art
Description will hereinafter be made with an electrophotographic copying apparatus taken as an example of the image formation apparatus.
In the electrophotographic copying apparatus, interchange of the photosensitive drum has often been done by removing or loading the photosensitive drum axially thereof by utilization of the drum shaft because of the ease with which the drum is mounted or dismounted or the accuracy of the mounting or dismounting of the drum is obtained. Also, a core positioning plate has been used to prevent the photosensitive drum from slipping out of the apparatus body after it has been loaded into the apparatus body, to control the axial position of the photosensitive drum and to accurately position the photosensitive drum relative to the optical system. Around the photosensitive drum, various members such as a developing device, a cleaner, a transfer paper transportation guide and a separator for separating transfer paper from the photosensitive drum are disposed in proximity to or in contact with the drum in accordance with the conditions of the process. Therefore, in order to mount or dismount the photosensitive drum with respect to the apparatus body, it has been necessary to release these members so that they withdraw from the photosensitive drum. If the mounting or dismounting of the photosensitive drum is effected without releasing these members, the surface of the photosensitive drum or the members may be injured or damaged.
Therefore, it has heretofore been practised to dispose an operating member for releasing the members in front of the aforementioned core positioning plate and to prevent the core positioning plate from slipping off unless the members are released, thereby preventing any malfunction. In this case, the malfunction can be prevented, but the operation of interchanging the photosensitive drum has been very cumbersome because it has involved the steps of releasing the members, thereafter removing the core positioning plate, and then mounting or dismounting the drum. For the purpose of preventing the malfunction, it has also been practised to make the operating member for releasing the members large in size and dispose it in the core positioning plate removal path, but this has led to an increased number of parts.
Recently, as shown in U.S. Pat. No. 3,985,436, there has been proposed an image formation apparatus in which, for example, a photosensitive drum, a developing device, a cleaner, a charger, etc. are constructed as a process unit and these may be interchanged at a time during the interchange of the photosensitive drum. In the case of such apparatus, the developing device or the cleaner need not be released even during the interchange of the photosensitive drum. However, it is difficult from the viewpoint of jam treatment to make the transfer paper transportation guide integral with the process unit and, as has heretofore been done, it is necessary to release the transfer paper transportation guide from the vicinity of the photosensitive drum during the interchange of the process unit. Thus, this image formation apparatus still suffers from the above-noted problems.